hampton



July 19, 1949. N. HAMPTON ELECTRICAL ELEMENT SUPPORTING MEANS 2 Sheets-Sheet 1 Filed Nov. 2, 1945 WVE/V TOR /L. N. HAMPTGN JW/ZQQE mid ATTORNEY 2 Sheets-Shet 2 ATTORNEF INVENTOR By L./V. HAMPTON %Zac%f)( 4 July 19, 1949.

Filed Nov. 2, 1945 3 I 0 (L/ 4 m I 4 5 G vivxw fi G H n uAzwvvfiww xx v hx\w-x-xv F 7/497,4 1 3 3 0 I l 5 I W |lh|l V5 7 h Z a 4 an a u. a M a a \N u a 3 v u .70 G H 9 .1 7 6 I I 1 4 wuwwwuxwwuuaw 3 4 a IT 5 4 4 6 3 5 4 4 v 4 5 5 4 T l 5 w w: J ply/MW 2 M W1 Id 1 w 7 a 0 6 II F3 I W" m 3 2 {H H 1 0 7 I I ll. 4 3 3 4.. 8 a a an n w. flaw. a w u Patented July 19, 1949 UNITED STA'iii;

ELECTRICAL ELEMENT SUPPORTING MEANS Application November 2, 1945, Serial No. 526,245

(ill. 20156) o saline.

This invention relates to electrical element supporting means and more particularly to means for supporting an electrical element in a body of an electrical device.

The object of the invention is to provide improved means for supporting an electrical element in a required place and position in a body of an electrical device.

The invention provides improved means for supporting and holding an electrical element in required place in a body provided with spaced walls defining a space to receive the electrical element.

A feature of the invention resides in a wedge device operable to hold a predetermined portion of the electrical element in a required place in the body. The wedge device per se is claimed in my copending application Serial No. 755,497, filed June 18, 1947, and ntitled Wedge device, and forming a division of the present application.

Another feature resides in stilt means operable to hold the electrical element elevated in the body.

To illustrate and explain the invention and not in the sense of a limitation thereof the invention is shown and described as embodied in an electrical control device that may be a rheostat or potentiometer.

In the drawings:

Fig. 1 is a top plan view of the electrical control device;

Fig. 2 is a view, partly in section, of a portion of the electrical control device and taken on the line 2-2 in Fig. 1;

Fig. 3 is a view, partly in section, of a portion of the electrical control device and taken in the line 3--3 in Fig. 1;

Fig. 4 is a top view, in section, of a portion of the control device and taken on the line l-d in Fi 3;

Fig. 5 is a side elevational view of a portion of the electrical element equipped with the stilt means and taken on the line 5-5 in Fig. 1;

Fig, 6 shows two parts in perspective of the wedge device; and

Fig. 7 is a view in perspective of the two parts shown in Fig. 6 and placed together in their relative positions for operation as a wedge device.

In some precision potentiometers now required the electrical resistance element must be held at required spaced points so that predetermined electrical potentials will be obtained when a wiper contact of the potentiometer reaches certain predetermined points on its course of travel along the resistance element. The predeter- 2 mined points on the resistance element must not shift relative to the body of the potentiometer during the operation of the potentiometer or under changes in temperature to which the potentiometer is subjected in service.

The potentiometer 1 shown in Fig. 1 comprises a body 8, a resistance element 9, a wiper contact it engaging the resistance element 9 and wedge device means H operating to support and hold the resistance element 9 at required spaced points in the body 8.

The body 8 is provided with spaced concentric walls l2, l3 and I' l extending from a base wall l5. Ribs 16 formed on the base wall l5 extend from the wall 12 to the wall l3 and provide strengthening means for portions of the base wall l5. The base wall 15 is centrally apertured to accommodate a rotatable shaft I! which extends upwardly in a space l'8 defined by the wall 2.

The rotatable shaft l1 carries an assembly of parts comprising a washer IS, an apertured arm 29, a T-shaped apertured arm 2|, a collector ring, not shown but disposed in the space i3 and a nut 22 to hold the other parts of the assembly on the shaft IT. The T-shaped arm 2! provides a supporting means for the wiper contact 55 which is mounted on the T-shaped arm 2! by means of screws 22. The wiper contact til is bifurcated to provide tines 23 and 24 across the free ends of which is secured a contact piece 25 operable to ride on an edge of the resistance ele ment 9. A heel portion 26 of the wiper contact iii is electrically connected to a lead wire 2? which is snubbed around a post 28 on the T- shaped arm 2| and extends beneath the apertured arm 20 to the collector ring not shown, the lead wire 2? being electrically connected to the collector ring. The T-shaped arm 2| and apertured arm 20 are channel-shaped in crosssection and are assembled to cooperatively form a hollow casing for a portion of the lead wire 21, the apertured arm 20 and the T-shaped arm it being held together in required assembled condition by means of a screw 28 or other suitable fastening means.

The walls l3 and I4 andthe base wall it in cooperation define an annular space 30 in the body 8. The upper portions of the walls l3 and M are shouldered to provide an upwardly extending outer flange 3! on the wall l3 and an upwardly extending outer flange 32 On the wall i l. The flange 32 extends above the plane of the flange 3!. The outer face of the wall l3 forms a cylindrical surface against which the resistance element 9 may be pressed by means of the wedge device means H. The inner face of the wall It is formed at spaced points to provide recesses 33 which extend downwardly in the wall M and open into the space 39. The recesses 33 extend downwardly from the shoulder 33 on the wall [4 to the base wall I5 and each recess 33 is of suificient width and length to accommodate one of the longer parts of a wedge device II, the structures and arrangement of which will be subsequently described. The upper portion of each recess 33 is tapered in depth to accommodate two parts of the wedge device H which when placed together in required position in the recess 33 form a wedge means to press the resistance element 9 toward the outer cylindrical surface of the wall 13. The deepest point of each recess 33 is at the top of the shoulder 36 of the wall 14. The recess 33 gradually decreases in depth to a point about halfway dow the wall M and then continues at an even depth to the base wall I 5.

The resistance element 9 may be of any form and construction found suitable for use in the potentiometer and of such dimensions that it may be readily accommodated in the space 39 in the body 8. The resistance element 9 shown in the drawings comprises a card-like support 35 supporting a resistance wire 36 which is wound in a plurality of turns on the card-like support 35. The resistance element 9 is somewhat flexible and may be bent to substantially follow the form of the outer surface of the wall [3. The thickness of the resistance element 9 is considerably less than the width of the space 39 in the body 9. The width of the card-like support 35 may be constant or may vary at certain points but its greatest width is usually not sufiicient to extend all the way down the wall 13 to the base wall l5. At least one edge of the resistance element 9 is made of even plane and this edge is used as the top of the resistance element 9 tobe engaged by the contact piece 25 of the wiper contact 19, the top of the resistance element 9 being disposed above the top of the wall l3 and in a plane with the line of travel of the contact piece 25.

At selected spaced points on the resistance element 9 stilt means 31 are provided to hold the resistance element 9 against undue downward movement in the space 30 in the body 8. Each stilt means 31 is secured at its upper portion to the resistance element 9 and extends downward therefrom a sufficient distance to engage the base wall l5 of the body 8 when the resistance element 9 is placed in required position for engagement by the wiper contact l9.

Each stilt means 31 as shown in the drawings is a laminated substantially stiff structure member comprising a strip 38 secured at its upper portion to the outer side face of the resistance element 9 and an apertured strip 39 somewhat wider than the strip 38 and secured to the outer surface of the strip 38 and in parallel relation therewith. The means employed to secure the strips 39 and 39 together and to secure the strip 38 to the resistance element 9 is a matter of choice. In the structure shown in the drawings the parts of the stilt means 3'! are secured together by means of a suitable cement and the strip 38 is secured by means of a suitable cement to the resistance. element 9 and apertures 40 are provided in the card-like member 35 to receive some of the cement 4| applied to the strip 38. The strip 39 is apertured at spaced points to provide apertures 42 for a purpose to be subsequently explained, the apertures 42 being located in the upper portion of the strip 39. A block 43 of about the thickness of the resistance element 9 is secured to the lower end of the strip 38 to space the lower end of the strip 38 from the outer face of the wall l3.

Each wedge device ll comprises a relatively long post member 94, a shorter wedge piece and a filling 93 of relatively low melting point material which has the characteristic of expanding as it solidifies. Examples of materials having the required characteristic will be subsequently given in this specification.

The post member 44 as shown in Fig. 6 is channel-shaped in cross-section and comprises two parallel side walls a! and 43 etxending angularly from a back wall 49 in the upper portion of which spaced apertures 59 are provided. An inwardly turned lug 5| is formed on the lower end of the back wall 99 to partially close the lower end of the post member 46. The side walls 57 and 58 are of constant width from the lower end of the post member 44 to a point about halfway to the top and then the side walls 9? and it gradually increase in width to the top of the post member 94 to provide sloping edge portions 52 suitable for engagement with the upper portion of the back wall-53 of the recess 33.

The wedge piece 45 as shown in Fig. 6 is channel-shaped in cross-section and comprises the parallel side walls 54 and 55 extending angularly from the front wall 56 which is apertured at spaced points 51. The wedge piece 35 is narrower than the post member 44 and is dimensioned so that it may be placed in the post member i l and may be moved longitudinally in the post member 44. Theside walls 54 and 55 of the wedge piece 95 gradually increase in width from the lower end of the wedge piece 95 to the top and so that the front wall 56 is of sloping form and when the edges 59 of the side walls 5 and 55 are placed in engagement with the inner surface of the back wall 49 of the post member i l the front wall 56 of the wedge piece 45 will fit against the upper and correspondingly sloping upper portion of the back wall 53 or" the recess 33. When the post member 44 and the wedge piece 45 are used as a wedge device the wedge piece 45 is nested in the post member 44 as shown in Fig. 7 and so that the edges 59 of the side walls 54 and 55 of the wedge piece 45 bear against the inner surface of the back wall 49 of the post member 33. When the post member' ld and the r wedge piece 95 are assembled as shown in Fig. '7

and the two parts 44 and A5 are placed in a recess 33 in the body 8 the'front wall 56 of the wedge piece 45 and the edges 52 of the side walls ll and 98 of the post member 4 3 bear against the sloping wall 53 of the recess 33. In this position when a downward thrust is applied to the wedge piece 45 the sloping portion of the wall 53 of the recess 33 acts in the nature of a cam to move the wedge piece 35 toward the wall I3 and this movement is imparted by the wedge piece 35 to the post member 99 which is correspondingly moved toward the wall l3.

The wedge devices H as shown in Fig. 1 provide means for holding the resistance element 9 in place in the body 8 at predetermined required spaced points and by means of the wedge devices H predetermined spaced points of the resistance element 9 are held in required positions relative to predetermined spaced points on the wall !3. The predetermined spaced points on the wall I 3 may be scratch mark reference points ll marked or otherwise formed on the wall Hi. The particular point of the resistance element 9 held by means of a wedge device H in register with a scratch mark ll on the wall I3 may be a predetermined turn of the wire 36 on the resistance element 8 so that a required electrical potential will be obtained when the wiper contact it comes into register with and in engagement with the particular turn of wire selected.

The parts 4 and 45 of the wedge device H when properly assembled form a laterally expansible, hollow post means and when placed a recess 33 and relative to a resistance element disposed in the space 36 in the body 8 form a ready means for initially and lightly holding particular point of the resistance element 9 in register with a predetermined reference point or scratch marl; H on the wall l3. In the initial use of the post member 44 and the wedge piece of the wedge device H in holding a required point on the resistance element 9 in required position in the body 3 relatively light or heavy pressures may be developed and applied to the resistance element 9 by means of the then employed parts 4e and 4.5 of the wedge device H to urge the resistance element 9 toward the wall l3. The pressure may be varied as required by longitudinally moving the wedge piece in the post member is and in the recess 33. While the resistance element 9 is lightly held against outward movement from the wall IS the resistance element 8 may be moved longitudinally to bring particular required point on the resistance element 8 in register with a mark H on the wall it. After the predetermined point on the resist- .nce element 9 is brought into register with a rei .ired reference point H on the wall I3 and the 1 ledge piece 45 is operated to make the post memer t l apply sufficient pressure to the resistance "lent to hold the required point on the rence element 9 in register with the reference hark ii, material to in molten condition and ...aving the characteristic of expanding during solidification is poured into the spaces defined by the post member 44 and the Wedge piece 45. AS previously stated examples of materials having the required characteristic will be subseouently given in this specification. The material in expanding applies pressure to the post member id and to the wedge piece 45 and urges the post member 4!; laterally relative to the wedge piece as and toward the wall 13 and increases the pressure applied by the post member 44 to the resistance element 9. Some of the material while in molten condition flows through the apertures 58 in the post member 44 and through the apertures 42 in the strip 39 and into engagement with the strip 39. Some of the material as also flows through the apertures 51 in the wedge piece 45 and into engagement with the wall 53 of the recess 33 The material 46 extending through the apertures and 51 upon solidification forms projections and S! of the material 46 to prevent displacement of the matecs the wedge piece 45. Some of the rial 45 while in molten condition passes ugh the lower end of the wedge piece 45 0 spaces 52 and es cooperatively ed by the post member 4 the wedge piece 45 the wall 53 of the recess 33, the space 62 -g defined by the walls 4! and 54 of the post member" is and the wedge piece 45, respectively, and the wall 53 of the recess 33, and the space 63 being defined by the walls 48 and of the post rial from the spaces defined by the post memi member 44 and the wedge piece 45, respectively,

and the wall as of the recess 33. Some of the material 46 also extends below the wedge piece is and to the lug 5| on the lower end of the 5 post member 44 and to the base Wall lb of the body 8 and fills the lower portion of the post member 44 and presses against the wall I4 to apply pressure to the lower end portion of the post member 4 to urge the block 43 against the wall 13. In Fi 2 the post member 524 and the wedge piece d5 are cooperating to urge the resistance element 9 toward the wall l3 to lightly hold the resistance element 9 in place in the body 8. In this case no expansible material (it has been applied. In Fig. 3 the wedge device H has been completed by placing the material 45 in the spaces provided. for its accommodation and the wedge device H is operating to hold the predetermined point of the resistance element 9 in required place in the body 8.

In Fig. 1 a plurality of wedge devices H are shown as holding predetermined points of the resistance element 9 in place in the body 8, the resistance element 9 is equipped with the stilt means 3?, and the stilt means 3'! are substantially in register with the recesses 33 in the body ii in which the wedge devices H are disposed. The stilt means in this illustration in addition to serving as elevating supports for the resistance element s also serve as spacing means and pressure distributing means between the wedge devices 5! and the resistance element 9. The stilt means 3?, however, might be located at positions other than in register with the wedge devices H and be replaced by other spacing strips since the main function of the stilt means is to hold the resistance element 9 against movement to a position below the edge of the wall 53 and principally during the time the wedge 40 devices H are being placed in the body 22 and conditioned to hold the resistance element i} in place in the body 8. In most cases, however, in constructing a potentiometer of the type shown the general location of points on the resistance element 9 at which required potentials may be obtained can be predetermined and the stilt means it! may be attached to the resistance element 9 substantially in register with these points. Before the wedge device it is completed by the addition of the material 45 and while the post member and wedge piece are operating to lightly hold the resistance element 2 in place the resistance element 5 with the stilt means 3'! attached thereto may be shifted from the initial position to bring a particular predetermined point of the resistance element in register with the reference marl: l! on the wall Iii. After the precise required adjustment of the resistance element 9 has been made the wedge piece :15 may be further pressed down in the recess 33 to make the post member M apply sufficient pressure on the resistance element 9 to hold the resistance element 9 against movement from the required position. The strip 39 of the stilt means 31 is wider than the wall 43 of the post member as and after final adjustment of the resistance elenent 9 has been made edge portions of the strip are bent over corners of the post member 44 s shown at 5/3 to tend to hold the stilt means ainst shifting on the wall 59 of the post some cases a lead wire 55 from the resistance element 3 is led through the wedge device H r and through an aperture in the base wall i5 and is connected to a terminal 61 mounted on the base wall it. The lead wire 65 may be readily extended to the terminal 61 by way of the space defined by the post member 4% and the wedge piece at before the material 46 is applied to complete the wedge device H.

To facilitate the making of the aperture 55 in the base wall 15 and indentation 68 may be formed in the base wall [5 to reduce the thickness of the base Wall [5 at the point where the lead wire 65 is to come through. The indentation 68 may be filled with a suitable material as shown at 69 after the lead wire 65 has been led through the aperture 66.

The materials from which the body 8, the stilt means 31 and the parts 44 and 35 of the wedge means H are made are matters of choice. The body 5 and the stilt means 3'! are shown, however, as being made of insulating material and the parts 44 and 45 of the wedge device I l are shown as being made of metal since such materials are obviously suitable for making these parts. If the body 8 and the stilt means 3'! are made of insulating material no insulating members are required between the resistance element 9 and the wall l3 and between the resistance element 9 and the means employed to urge the resistance element 9 toward the wall it. When the wall 13 of the body 8 is made of an insulating material molded into form and somewhat frangible, fracturing of the wall is by the pressures applied by the wedge devices 9 i may be prevented in most cases by first conditioning all wedge devices ll employed to apply relatively light pressures to the resistance element 9 to urge the resistance element 9 toward the wall l3 and by then further adjusting the wedge pieces 45 in diametrically located positions to increase the pressures. After the wedge pieces d5 have all been adjusted to obtain sufilcient pressures to hold the resistance element 9 against movement from the predetermined points the danger of localizing the pressures created by the application of the material ldto the other parts of the wedge devices It may be reduced by applying the material 46 to the wedge parts located at diametrical positions rather than proceeding in a clockwise or counter-clockwise manner to complete the wedge devices I l by the addition of the material 46.

Since the resistance element ii is only held in place at spaced points portions of the resistance element 9 between the held points may bulge away from the wall l3 as shown at ill in Fig. 1. Under changes in temperature and difl'erential expansion or contraction of the body 8 and the resistance element 8 there may be some relative movement of the resistance element 9 and the wall l3 between the points at which the resistance element 9 is held but the wedge devices ll will hold the critical predetermined points of the resistance element 9 against movement relative to the reference marks H on the wall It.

The material 46 is shown in the drawings as being metal but may be any other material found suitable for the purpose and having the characteristic of expanding during solidification of the material.

For example, a metal alloy of a type generally known as Woods alloy may be used as the fillin material 46 provided that it has the required characteristic. Some metal alloy compositions of the type generally known as Woods alloy When reduced to a, molten condition and then allowed to set have the characteristic of set.

Composition Bismuth Lead Tin Cadmium Antimony Alloy #1 48.0 28.5 14.5 9.0 Alloy#2 50.0 26.7 13.3 10.0

Some cementitious materials will also expand as they progress from a plastic condition to a condition of permanent set. For instance, cement containing ammonium chloride, iron powder and sulphur expands while progressing from a plastic condition to acondition of permanent set because the iron powder changes to iron oxide which has a volume about ten times greater than the iron from which it came.

What is claimed is:

1. In an electrical control device a body, spaced walls in said body defining a space in said body, an electrical element located in the space defined by said walls and a wedge device positioned between one of said walls and said electrical element and operating to urge said electrical element toward another of said walls and holding said electrical element in place in said body, said wedge device having a filling of material in solid set condition and that has expanded in setting.

2. In an electrical control device, a body, spaced walls in said body defining a space in said body, an electrical element disposed in the space defined by said walls, an expansible wedge device mounted in one of said walls and operating to urge said electrical element toward another of said walls to hold said electrical element in place in said body and a filling of material in pcrmanent solid set condition in said wedge device, said material having expanded in reac iing a condition of permanent set.

3. In an electrical control device a body, spaced walls in said body defining a space in said body. an electrical element disposed in the space d fined by said walls and expanded wedge device means mounted at spaced points in one of said walls and operating to hold said electrical element at spaced points along another of said walls, each of said wedge device means having a filling of solidifiable material applied in nonsolid condition and operating to expand during setting of the material.

4. In an electrical control device in which a body is provided to house an electrical element supporting means for the electrical element com-- prising, in combination, spaced walls in the body defining a space to accommodate the electrical element, a channeled wedge piece, a channeled post member receiving said channeled wedge piece and cooperating with said channeled wedge piece to form a laterally expansible hollow post means, said hollow post means being disposed between the electrical element and one of said walls and a fillin of solidifiable material appliable in non-solid condition and having the characteristic of expanding upon solidification entered in the hollow post means and laterally expanding the hollow post means and making the hollow post means urge the electrical element toward one of said walls to hold the electrical element in required place in the body.

5. In an electrical control device in which a body is provided to house an electrical element, supporting means for the electrical element comprising, in combination, spaced walls in the body defining a space to accommodate the electrical element, a recess formed in one of said walls and opening into the space defined by said walls, a channeled post member disposed in said recess, a channeled wedge piece entered in said channeled post member and bearing against the wall in which said recess is formed, said channeled post member and said channeled wedge piece cooperating to form a laterally expansible hollow post which is disposed between one of said walls and the electrical element and being operable to press the electrical element toward one of said walls, spacing means between said laterally expansible hollow post and the electrical element and a solid filling of solidifiable material appliable in liquid form and having the characteristic of expanding upon solidification entered in said laterally expansible hollow post and operating to hold said hollow post in laterally expanded condition to make said laterally expansible hollow post urge the resistance element and. said spacing means toward one of said walls to hold the resistance element in place in the body.

6. In an electrical control device a body, spaced walls in said body defining a space in said body, an electrical element located in the space defined by said walls, a hollow wedge device means disposed between one of said walls and said electrical element and operating to urge said electrical element toward another of said walls to hold said electrical element in place in said body, a filling of material in said hollow wedge device means and expansible with time and a lead wire connected to said electrical element and extending through said filling of material in said hollow wedge device means and outwardly of said body.

7. In an electrical control device a body, spaced walls in said body defining a space in said body, an electrical element located in the space defined by said walls, channeled members disposed between one of said walls and said electrical element and forming a laterally expansible post means to urge said electrical element toward another of said walls to hold said electrical element in place in said body, a conductor connected to said electrical element and extending longitudinally through said channeled members and a filling of material in said channeled members and operating to laterally expand said post means, said filling of material bein appliable in non-solid condition and operating to set up solid and expand with time to a condition of permanent set.

8. In a variable electrical resistance control device a body, spaced upright walls and a base wall in said body defining a space in said body, a card-like resistance element disposed edgewise in the space defined by said walls, a wiper contact operable along and in engagement with an edge of said resistance element, stilt means secured to said resistance element and extending therefrom into engagement with said base wall and operating to support said resistance element in position for engagement by said wiper contact, recesses formed at spaced points in one of said upright walls and opening into the space defined by said walls, inclined walls in said recesses and facing the opposite upright wall and wedge device means disposed in said recesses and engaging said inclined walls and operating to press said resistance element and said stilt means toward the opposite upright wall and hold said resistance element at spaced points and against movement relative to said body at the spaced points, said wedge device means having fillings of solidifiable material appliable in non solid condition and having the characteristic of expanding and taking a permanent set with time.

LEON N. HAMPTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

